Fuel supply systems for internal combustion engines



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R. CLARK Ji mmn f, mm

FUEL SUPPLY SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed Jan. 9, 1968 United States Patent U.S. Cl. 123--1]l9 7 Claims ABSTRACT OF THE DISCLOSURE A fuel system for an internal combustion engine comprises a throttled inlet manifold, a pump for supplying liquid fuel to at least one nozzle in the manifold, means responsive to manifold pressure and further means responsive to manifold temperature for controlling a valve whereby fuel flow to the manifold nozzle is controlled.

This invention relates to fuel supply systems for piston and cylinder type internal combustion engines of the kind in which liquid fuel is injected through one or more nozzles, either into a manifold through which a stream of air for combustion flows or immediately before entry of the air into the cylinder of the engine.

In order for such a system to be satisfactory for use on an aircraft engine, it is desirable that it should be sensitive to changes in various parameters related to operating conditions.

The object of the invention is to provide a fuel supply system for a piston and cylinder type internal combustion engine having a manifold through which, in use, a stream of air for combustion enters the engine, a manually controllable throttle in the manifold for limiting said supply of combustion air, said system comprising one or more liquid fuel injection nozzles arranged to supply liquid fuel into the stream of combustion air, a pump to provide a supply of liquid fuel to said nozzle or nozzles means responsive to the pressure obtaining in the manifold, and further means responsive to the temperature obtaining in the manifold.

The invention will now be described by way of example with reference to the accompanying drawings in which The single figure is a diagrammatic representation of one form of system constrncted in accordance with the invention, and

The system illustrated is intended for use to supply liquid fuel into a stream of pressurized air for combustion entering the engine, and is particularly suitable for use in conjunction with engines intended for use upon aircraft.

The supply of pressurised air in a manifold 10 of the engine is provided by a turbo super-charger indicated at 11 which is driven through a shaft 12 from a source of power (not shown). Upstream of the super-charger 11 is a manually controllable throttle 13 arranged to control the supply of air which can reach the engine through the manifold 10. The liquid fuel system is intended continuously to supply liquid fuel to one or more injection nozzles 14 disposed immediately upstream of the impeller of the super-charger 11.

The system incorporates a centrifugal pump 15 which is engine driven through gearing 16, the pump deriving a supply of fuel from a reservoir 17 through a filter 18. Delivery takes place through a spring-loaded ball valve 19. The main flow of fuel from the pump takes place through a passage 20, and into a metering device 21 having a body 22 within which is disposed a slidable sleeve 23 which is provided with at least one triangular opening 24. The volume of fuel which can flow through the triangular opening or openings 24 is determined by the position of the sleeve 23 within the body 22 and also by the position of a spring loaded further sleeve 25 which surrounds the sleeve 23 and which is also slidably mounted in the body 22. The metered fuel from the device 21 fiows along a passage 26 to a valve 27 having in a body 28 a diaphragm 29 carrying a valve closure member 30 which is arranged to control the flow of fuel through a passage 31 to the nozzle 14 in the manifold 10 of the engine, there being a non-return valve 32 in the passage 31.

Flow of fuel through the device 21 is controlled, as previously referred to, by the position of the sleeve 23 with respect to the body 22, and the sleeve 23 is in turn controlled by a temperature sensitive device indicated at 33 in an extension of the body 22 of the device 21, the interior of this extension being in communication with the inlet manifold 10 of the engine at a position downstream of the super-charger 11, so as to partake of temperature conditions obtaining therein. The element 33 comprises a plurality of bimetallic washers arranged in a stack, the length of which varies in accordance with the temperature obtaining in the manifold 10.

The device 21 also includes a manual control 34 connected to a cam 35 which, when in the position shown, permits the sleeve 25 to move under the influence of its spring 36 substantially to increase the area of the triangular opening or openings 24 in order to provide an increased quantity of fuel for starting purposes.

The system also includes a device 37 which is arranged to control the spill of fuel from a position downstream of the pump 15 and upstream of the device 21. This device 37 includes within a body 38, a lever 39 which is arranged by means of a knife edge 40 carried thereby to control the flow of fuel through a passage 41 which communicates with the passage 20 between the pump 15 and the device 21, the body 38 having an escape passage 42 leading to the upstream or inlet side of the pump 15. The position of the lever 39 and therefore the quantity of fuel which is spilled through the passages 41 and 42 is determined by the relative positions of two capsules 43, 44 the former having its interior communicating through a passage 45 with the inlet manifold 10 of the engine downstream of the supercharger 11, and the latter capsule 44 being evacuated. Thus pressure conditions in the inlet manifold 10 of the engine determines the rate of spill of fuel through the passages 41 and 42, but in this example, the capsule 44 has an additional compartment indicated at 46 which through a passage 47 is arranged to communicate with the exhaust system of the engine, so that the pressure conditions existing therein can be exerted upon the lever 39, thus modifying its response to the pressure in the engine inlet manifold 10.

The pressure in the passage 42 is exerted at the opposite side of the diaphragm 29 of the valve 27 through a passage 48, a balance being achieved at opposite sides of the diaphragm 29 to control the flow of fuel to the nozzle 14 along the passage 31. The valve 27 also includes a manual control 49 connected to a cam 50, which can be actuated to move the valve closure member 30 so as to cut off flow of fuel along the passage 31 to the nozzle 14.

It is to be understood that the pressure of the fuel leaving the pump 15 is a function of engine speed, this also determining the position of the valve closure member 30 in accordance with the pressures exerted at opposite sides of the diaphragm 29.

The passage 42 includes a device 51 which affords a restriction for the flow of fuel, this device also being arranged to vary the flow through the passage 42 in accordance with changes in fuel temperature, though it is to be understood that this device could be replaced where fuel temperature changes are insignificant by a fixed restrictor in the passage 42. The restrictor in the device 51 together with the restriction afforded by the knife edge 40 in the device 37 provide an intermediate pressure which is exerted through the passage 48 upon the diaphragm 29, and adjustment can be achieved in any convenient manner to provide a satisfactory balanced position for the valve closure member 30 under specified running conditions of the engine.

In the event of failure of the centrifugal pump 15 or for starting purposes, there is also provided a positive dis placement pump which in this example is of gear type, indicated at 52, which is connected in parallel with the pump 15, but there is also provided a spill passage 53 downstream of this pump 52 which incorporates a pressurising valve 54 so that excess fuel delivered by this pump is returned to the inlet side thereof through a passage 55.

It will be understood therefore that the system provides a continuous supply of fuel to the inlet manifold of the engine, and is responsive to engine speed when the centrifugal pump is in use, to inlet manifold temperature through the element 33, to inlet manifold pressure through the device 37 and also to the back pressure in the exhaust system of the engine through the passage 47, and furthermore, in this example, it is sensitive to fuel temperature through the device 51.

Furthermore, the system can be modified to provide additional variations of the fuel supply in accordance with other parameters as may be desired.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A fuel system for a piston and cylinder type internal combustion engine comprising an induction manifold for entry of air for combustion to the engine, a manually controllable throttle in the manifold for controlling the supply of air, a fuel injection nozzle arranged to supply liquid fuel into the stream of combustion air, a pump to provide a supply of liquid fuel to the nozzle, passage means between the pump and the nozzle, a throttle valve in said passage means, a spill passage connected to the passage means between the pump and the throttle valve for the escape of excess fuel, a pressure responsive device in said spill passage, said pressure responsive device being 4 responsive to the air pressure in the manifold to control the flow of liquid to the spill passage, and a temperature responsive device connected to the throttle valve, said temperature responsive device being responsive to the temperature of the air in the manifold.

2. A fuel system as claimed in claim 1 in which the manifold has a turbo super-charger which pressurises the air flowing to the engine, through the manifold, the nozzle being disposed in the manifold at a position upstream of the super-charger.

3. A fuel system as claimed in claim 1 in which the pressure responsive device comprises a capsule communicating with the manifold, said capsule controlling a valve member whereby the spill of fuel is controlled.

4. A fuel system as claimed in claim 1 in which the throttle valve has a manual control whereby the fuel supplied to the nozzle can be enriched.

5. A fuel system as claimed in claim 1 in which there is a further valve in the passage means between the throttle valve and the nozzle, said further valve being controlled in accordance with the pressure of fuel in the system.

6. A fuel system as claimed in claim 1 having a device responsive to changes in the fuel temperature, said device being disposed in the spill passage.

7. A fuel system as claimed in claim 1 in which the pump is engine driven and there is a further pump arranged to supply fuel to the nozzle when the associated engine is being started.

References Cited UNITED STATES PATENTS 2,419,171 4/1947 Simpson et al. 123-119 2,502,997 4/1950 Schnaible 123-119 2,623,509 12/1952 Gold et al 123119 2,667,918 2/1954 Ifield 123140.3 2,806,519 9/1957 Barford et al 123140.3 2,852,011 9/1958 Pringham 123119 2,876,755 3/1959 Gold et al 123119 3,320,938 5/1967 Homfeld et al. 123139 LAURENCE M. GOODRIDGE, Primary Examiner US. Cl. X.R. 

